There is known a game system which is configured so as to give a motivation to play a game repeatedly to a player in such a way that, while at least a part of plural tasks prepared for a game, for example, one or plural tasks which has/have a comparatively low difficulty level is/are in a status that it is permitted that the task(s) can be selected by a player, the other tasks are in a status that these tasks are forbidden to be selected, and in a case that a task already selected is accomplished, it is permitted to select at least one task, the selection of which has been forbidden before then (for example, a patent literatures 1 and 2).    Patent Literature: PTL1: JP-A-2001-87545 and PTL2: JP-A-2001-276422.